In the global quest for effective cancer treatments, researchers are uncovering promising strategies in the most unexpected of places: the very viruses we typically strive to avoid. Pathogens such as the common cold and influenza, once seen solely as threats to our health, are now being studied for their potential to target and destroy cancer cells. This concept, while not entirely new, has shown enough success to warrant extensive exploration across various viruses and types of cancer.
Dr. Shashi Gujar, a cancer researcher and professor at Dalhousie University, specializes in immunotherapy and is at the forefront of this innovative approach. “We know we can engineer almost any virus to do this because as long as a virus is safe and not causing any disease, we can engineer them to be used as cancer therapies,” says Dr. Gujar. He emphasizes the vast potential of this technology but also stresses the importance of developing it with rigorous global standards to ensure safety and efficacy, accelerating its availability to cancer patients.
To facilitate this, Dr. Gujar, along with international colleagues such as Dr. Guido Kroemer of the Center de Recherche des Cordeliers in Paris and Dr. John Bell of the University of Ottawa, has authored a comprehensive guide published in the journal Nature Protocols. This paper provides standardized guidelines for the design, production, and testing of oncolytic viruses (OVs), a type of cancer treatment that employs viruses to attack and kill cancer cells while also stimulating the immune system to fight the cancer more effectively.
Turning Enemies into Allies
Oncolytic viruses represent a novel class of cancer immunotherapy agents. They not only infect and destroy cancer cells but also bolster the body's antitumor immunity. Dr. Gujar explains that our immune system is adept at identifying and responding to threats like viruses and bacteria, recognizing them as foreign and launching an attack. Cancer cells, however, often evade detection because they share characteristics with healthy cells, allowing them to proliferate unchecked.
Decades ago, scientists observed that some cancer patients who developed infections reported a reduction or disappearance of their cancer. More recent observations suggest that cancer patients who contracted COVID-19 experienced cancer regression post-recovery. These insights have led researchers to consider whether viruses, which naturally attract a strong immune response, could be harnessed to target and eliminate cancer cells.
“That's what these viruses do—they get the attention of your immune system and direct it to attack the cancers,” says Dr. Gujar. “It's almost like an indirect vaccination. For instance, if you want to train your immune system to fight COVID-19, you get a COVID vaccine. Similarly, to train your immune system to combat cancer, you use an oncolytic virus.”
From Testing to Therapy
Before oncolytic viruses can be deployed as a treatment, they must undergo rigorous testing to ensure they do not cause illness and are selective in targeting cancer cells. Countries like the United States, China, Europe, and Japan have approved OV technology for treating cancers such as melanoma, using viruses like herpes simplex, reovirus, measles, and adenovirus. Canada, although not yet approving OV therapy, remains a leader in OV research, boasting some of the world's largest labs dedicated to its development.
Dr. John Bell, one of the pioneers in OV research in Canada and a co-author of the Nature Protocols paper, highlights the importance of establishing best practices in this burgeoning field. The guidelines cover everything from the selection and characteristics of suitable viruses to the procedural steps required to advance to clinical trials.
“Exciting new clinical data from various oncolytic viruses is generating considerable enthusiasm in the field,” notes Dr. Bell. “It is crucial to set rigorous standards to allow for the comparison of safety and efficacy of these innovative virus products.”
Source: Dalhousie University